1. Field of the Invention
The present invention relates to a radiation image signal output control method and apparatus for controlling output of wireless communication signals from an output unit that reads out image signals from a radiation image recording medium according to a radiation image stored therein and outputs the image signals after converting to wireless communication signals.
2. Description of the Related Art
Various radiation image recording media constructed to receive radiation representing a radiation image to record the radiation image therein are proposed and put into practical use in the medical and other industrial fields.
Such radiation image recording media include, for example, a radiation image detector formed of a semiconductor material that generates electric charges when irradiated with radiation, and such radiation image detectors proposed include so-called “optical readout type” and “TFT readout type” radiation image detectors.
One of the optical readout type radiation image detectors proposed, for example, is constituted by a layer structure that includes the following layers in the order listed below: a first electrode layer that transmits radiation; a recording photoconductive layer that generates electric charges when irradiated with radiation; a charge transport layer that acts as an insulator against the latent image charges and as a conductor for the electric charges of opposite polarity to the latent image charges; a readout photoconductive layer that generates electric charges when irradiated with readout light; and a second electrode layer that includes line electrodes that transmit readout light disposed in parallel with each other. In the radiation image detector described above, radiation representing a radiation image is irradiated on the detector from the side of the first electrode layer, and the radiation image is recorded in the detector by storing electric charges generated in the recording photoconductive layer in accordance with the radiation irradiated thereon in the interface between the recording photoconductive layer and charge transport layer. Thereafter, the detector is scanned with linear readout light in the longitudinal direction of the line electrodes to generate electric charges in the readout photoconductive layer. The electric charges generated in the readout photoconductive layer combine with the electric charges stored in the interface described above and flow out to the line electrodes, which are integrated by a current detection amplifier connected to each of the line electrodes, thereby image signals are obtained from the detector, i.e., the radiation image is read out from the detector.
Further, another type of radiation image recording medium that uses a storage phosphor sheet is also proposed. The storage phosphor sheet is provided on a support medium and a radiation image is stored and recorded thereon by the irradiation of radiation transmitted through a subject. The radiation image recorded on the storage phosphor sheet is read out as image signals by photoelectrically converting stimulated luminescence generated by the irradiation of excitation light on the sheet, such as a laser beam or the like.
Further, a portable cassette constituted by one of the radiation image recording media described above, a readout unit, and the like accommodated in a case is also proposed, which allows recording and reading out of a radiation image at any place, as well as at a predetermined place. Further, a method, in which image signals are outputted from such a portable cassette as wireless communication signals, which are received by a receiving unit such as a computer or the like to display the radiation image on a display as a visible image based on the received wireless communication signals is also proposed as described, for example, in Japanese Unexamined Patent Publication No. 7(1995)-140255.
However, when the image signals are outputted as wireless communication signals in the manner as described above, it is likely, for example, that the wireless communication signals are intercepted by a third individual who is totally unrelated to the hospital where such wireless communication is conducted. This may lead to leakage of the personal information of a patient.
The present invention has been developed in view of the circumstances described above, and it is an object of the present invention to provide a radiation image signal output control method and apparatus which, when radiation signals are outputted as wireless communication signals in the manner as described above, is capable of preventing random interceptions of the wireless communication signals.